Heat and Temperature

Temperature And Heat

Temperature is a physical quantity that indicates the internal energy of a body, object or environment in general. Heat is the exchange of thermal energy between two bodies that have different temperatures. Heat flows from high-temperature areas to low-temperature areas.

6.1

Temperature And Heat

Heat is a form of energy that is transferred because there is a difference in temperature
A material will become hotter when it receives heat, and will become colder when it loses heat
Heat cannot be seen but its presence can be felt.
Heat moves as energy waves, similar to other types of energy
Heat can change the state of a substance when the substance is heated or cooled
Heat can be released through chemical reaction. Heat is released together with other types of energy such as light.

Temperature

Temperature is a degree of measurement for hotness or coldness in a substance.
The temperature is measured using a thermometer.
The standard unit of temperature is degrees Celsius (symbol: ºC)
There are also other units of temperature measurement, namely degrees Fahrenheit (ºF) and degrees Kelvin (K).

Thermometer

The liquid in the thermometer will expand or shrink when exposed to different ambient temperatures
As the temperature of the substance decreases, the level of the liquid in the thermometer will decrease as the liquid shrinks
As the temperature of the substance increases, the level of the liquid in the realm of the thermometer will increase as the liquid expands

The correct techniques to measure temperature:

Hold the thermometer upright at the upper stem. Do not hold the bulb because the heat from our body will affect the temperature reading.
Immerse the bulb in the water. Do not let the bulb of the thermometer to touch the bottom or the sides of the container.
When taking a reading, place your eyes at the same level of the meniscus of the liquid in the thermometer.

Expansion and contraction of matter

Matter is made of small particles called atoms. It exists as solids, liquids, and gases.
When a matter is heated, it gains heat.

Heat energy causes the atoms to move faster.
The atoms begin to move away from each other.
As a result, the volume of matter increases, and the matter expands.

When a matter is cooled, the atoms in it loses heat energy.

Atoms will move slowly and become closer to each other.
As a result, the volume of matter decreases and the matter contracts.

Importance of application of expansion and contraction of matter

Mercury in the thermometer

The mercury in the thermometer will expand when hot and will contract when cold
This enables the temperature to be measured

Electric and telephone cables

Cables are mounted loosely to prevent them from snapping when they contract in cold weather

Railway tracks

Railway tracks are built with gaps between the tracks to allow expansion during hot weather
The gaps prevent the railway tracks from bending

Concrete slabs on pavements

Concrete slabs are arranged with gaps in between them to allow expansion during hot weather.
This will prevent the concrete slabs from cracking.

Temperature And Heat

6.1

Temperature And Heat

Heat is a form of energy that is transferred because there is a difference in temperature
A material will become hotter when it receives heat, and will become colder when it loses heat
Heat cannot be seen but its presence can be felt.
Heat moves as energy waves, similar to other types of energy
Heat can change the state of a substance when the substance is heated or cooled
Heat can be released through chemical reaction. Heat is released together with other types of energy such as light.

Temperature

Temperature is a degree of measurement for hotness or coldness in a substance.
The temperature is measured using a thermometer.
The standard unit of temperature is degrees Celsius (symbol: ºC)
There are also other units of temperature measurement, namely degrees Fahrenheit (ºF) and degrees Kelvin (K).

Thermometer

The liquid in the thermometer will expand or shrink when exposed to different ambient temperatures
As the temperature of the substance decreases, the level of the liquid in the thermometer will decrease as the liquid shrinks
As the temperature of the substance increases, the level of the liquid in the realm of the thermometer will increase as the liquid expands

The correct techniques to measure temperature:

Hold the thermometer upright at the upper stem. Do not hold the bulb because the heat from our body will affect the temperature reading.
Immerse the bulb in the water. Do not let the bulb of the thermometer to touch the bottom or the sides of the container.
When taking a reading, place your eyes at the same level of the meniscus of the liquid in the thermometer.

Expansion and contraction of matter

Matter is made of small particles called atoms. It exists as solids, liquids, and gases.
When a matter is heated, it gains heat.

Heat energy causes the atoms to move faster.
The atoms begin to move away from each other.
As a result, the volume of matter increases, and the matter expands.

When a matter is cooled, the atoms in it loses heat energy.

Atoms will move slowly and become closer to each other.
As a result, the volume of matter decreases and the matter contracts.

Importance of application of expansion and contraction of matter

Mercury in the thermometer

The mercury in the thermometer will expand when hot and will contract when cold
This enables the temperature to be measured

Electric and telephone cables

Cables are mounted loosely to prevent them from snapping when they contract in cold weather

Railway tracks

Railway tracks are built with gaps between the tracks to allow expansion during hot weather
The gaps prevent the railway tracks from bending

Concrete slabs on pavements

Concrete slabs are arranged with gaps in between them to allow expansion during hot weather.
This will prevent the concrete slabs from cracking.

Temperature And Heat

Temperature And Heat

Chapter : Heat

Topic : Heat and Temperature

Related notes